Mrs Webb, of Three Kings, said it was time she thanked those who helped both her son survive and her endure the ordeal of having a premature baby. She started running on Alex's birthday, November 30.
"I knew at some point I wanted to fundraise and now that he's a bit older and a bit better, it just seemed the right time to do it. The idea came to me as I was running," she said.
Before starting her 720km challenge, Mrs Webb was already a runner and she enjoys being fit, though she admits she's "more of a plodder than a runner".
The sheer distance and commitment of the feat will push her to her limits. At the moment she's running about 20km a day, and despite the usual chaffing and blisters and a few "niggles" with her joints, she's tracking well.
She is trying to push herself a bit further every day so she can run 51km on January 17 - the day Alex was discharged two years ago.
"I really wanted to set myself a challenge that I would really struggle with. I didn't want it to be a breeze. And this is a challenge ... "
The hardest part about having a child in the neonatal unit was being forced to leave them there and go home, she said. Mrs Webb said she wanted to replicate that struggle with her running.
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